| The development of industry is making the environmental pollution more and moreserious, bringing great hazard to human beings' living circumstance. Nowadaysenvironmental protection for realization of sustainable development has become thekey point of current economic development, and thus technology and instrumentexploitation of monitoring system for detecting trace gases in the air and pollutantsource is an important prerequisite for bettering our environment. Based on theprinciple of trace gas monitoring with UV spectroscopy, the application of DifferentialOptical Absorption Spectroscopy (short as DOAS) in trace gas monitoring system andContinuous Emission Monitoring System (short as CEMS) is presented.The main content of my thesis is listed as follows.Firstly, data processing method of our DOAS atmospheric pollutant monitoringsystem is given. This process includes six steps, i.e., process of standard absorptioncross-section, preparation of background spectra, filtering process to improve spectraquality, calculation of optical depth and differential cross-section, and concentrationretrieval by multiple linear regression method. The DOAS data processing can beconcluded into two main procedures, standard spectra processing and sample spectraprocessing of gases of interest.Secondly, systematic design of our DOAS system is introduced with emphasis ondesign and realization of the system control software. Here object-orientedprogramming (known as OPP) is applied in the software development. The process toachieve functions of spectra registration, communication with PM10 monitor andmeteorologic instrument and retrieval of gases concentration is given in details andthe design of database is also described. MSComm in VB is applied for thecommunication of PM10 monitor and the meteorologic instrument with the wholesystem, based on RS485 protocol and RS432C protocol, respectively, and thusintegrates these two parts into the monitoring system. OPP is used for database design,and database access method based on storage process is established, which improvesthe efficiency. This control software also holds functions required for a monitoringsystem such as annual, monthly and daily report.Thirdly, it comes to experiment. Standard gas experiment in the sample cell isconducted, and comparison experiment is performed between our DOAS system andDOAS-4R produced by Eridan-1 from Russia as well. The accuracy, reproducibilityand linearity are evaluated. Experimental result shows the measurement error iswithin 2% with an excellent reproducibility and linearity. Besides, comparisonexperiment indicates that relative measurement error of SO2 and NO2 for these twosystems is 5.46% and 3.12%, respectively, and their correlation coefficient is 0.9947and 0.9666. Thus, we can believe that the measurement result of our system is highlytrusted and it even possesses internationally advanced technique.Finally, preliminary study is carried on CEMS---another application of DOAStechnique. Theory and principle study is conducted on two main problems in CEMS,effect of high temperature on absorption cross-section and nonlinearity ofLambert-Beer theory. According to current research, a solution to temperatureproblem is presented, which would provide a sound basis for further study.
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